Ether terminated polycarbonates



3,080,342 ETHER TERMDIATED PGLYCARBGNATES Lieng-Huang Lee and HennoKesldtula, Midland, Mich, assignors to The Dow Chemical Company,Midland, Mich a corporation of Delaware No Drawing. Filed May 31, 1960,Ser. No. 32,614 '7 Claims. {CL 260-47) This invention relates to new andimproved polycarbonate resins. More particularly it relates to highmolecular weight polycarbonate resins having improved propertiesespecially with regard to thermal stability and ease of fabrication.

It is known that polycarbonate resins can be made which have exceptionalstrength and outstanding toughness. However, these resins are difficultto fabricate from a melt thereof because they have very high viscositiesat temperatures slightly above their melting points. It has beensuggested that this difficulty can be overcome by fabricating highmolecular Weight polycarbonate resins at temperatures substantiallyabove their melting points. When, however, a polycarbonate resin isheated to a temperature substantially above its melting point in orderto fabricate it at a lower viscosity the polymer degrades and theresultant products have considerably reduced values for strength,toughness, heat resistance, transparency and other desirable properties.

It is among the objects of this invention to provide new and improvedpolycarbonate resins.

A further object of this invention is the provision of such polymerswhich can easily be fabricated from melts thereof into shaped articles.

A particular object of the present invention is the provision of highmolecular weight polycarbonate resins which are thermally stable andhave low melt viscosities.

Other objects and advantages of the present invention will be evident inthe following description.

It has now been discovered that high molecular Weight polycarbonateresins having certain terminal groups on the polymer chains haveimproved properties, particularly low melt viscosity and a high thermalstability. According to the present invention polycarbonate resinshavingterminal groups obtainable by removing the hydroxyl hydrogen fromcertain glycol ethers have low viscosities at temperatures above theirmelting points and high thermal stability.

The glycol ethers that can be used as terminators to form the resins ofthe present invention are monohydroxy compounds corresponding to theformula in which R is a hydrocarbon radical having from 1 to 12 carbonatoms and is free of aliphatic unsaturation, R and R' are independentlyselected from the group consisting of H methyl and ethyl, and'the sum ofthe carbon atoms in R" and R is from 0 to 2, and n is a positive integerfrom 1 to 3. Representative examples of compounds suitable as chainterminators in accordance with the present invention are ethylene glycolmethyl ether, ethylene glycol phenyl ether, ethylene glycol ethyl ether,ethylene glycol n-butyl ether, diethylene glycol methyl ether,diethylene glycol ethyl ether, diethylene glycol n-butyl ether,propylene glycol methyl ether, dipropylene glycol methyl ether,dipropylene glycol n-butyl ether, tri- 65 propylene glycol'methyl ether,ethylene glycol t-butyl ether, ethylene glycol cyclohexyl' ether,ethylene glycol nonyl ether, ethylene glycol dodecyl ether, propyleneglycol phenyl ether, propylene glycol n-butyl ether,

propylene glycol dodecyl ether, diethylene glycol undecyl 79ether,'dipropylene glycol cyclohexyl ether, tripropylene glycol t-butylether, tripropylene glycol octyl ether, tri- 3,080,342 Patented Mar. 5,1963 brewin which OA-O represents the divalent residue which can beobtained by the removal of hydroxyl hydrogens from an organic dihydroxycompound free of aliphatic unsaturation, T represents the monovalentresidue which can be obtained by the removal of reaction hydrogen from achain terminator of the present invention and n is a positive integergreater than 20 and preferably greater than 40.

The divalent residue can be obtained from a glycol such as ethyleneglycol, tetramethylene glycol, hexamethylene glycol, 1,4-dihydroxycyclohexane, and decamethylene glycol. Preferably, however, the divalentresidue -O-A-O- is obtained from compounds represented by the formulaH'OAr-BArO-H and forming polymers represented by the formula in which Arand Ar are divalent benzene nuclei, that is, phenylene and substitutedphenylene, and B is a divalent aliphatic or cycloaliphatic radical,oxygen or sulfonyl. Preferably, B is alkylidene or cycloalkylidene, thatis, Ar and Ar are joined to the same carbon atom of the B radical. Arand Ar are preferably linked into the polymer chain at the l and 4positions, the 4 positions being linked to B and the '1 positions beinglinked to oxygen in the polymer chain. When Ar and Ar arefurther'substituted, the substituents are preferably in the 2 and/ or 6positions. Illustrative examples of the B portion of the polymer in theabove formula when B is alkylidene are methylene, ethylidene, propylidene, isopropylidine, 2,2-butylidene, 4-methyl-2,2-butylidene, andcyclohexylidene. Representative examples of Ar and Ar substituents aremethyl, ethyl, isopropyl, Z-tertiary-butyl, phenyl and chloro.

'The' organic dihydroxy compound is preferably a diphenol, especially analkylidene diphenol. Representa. tive examples of alkylidene diphenolsuseable as a base material for making polycarbonate resins of thisinvention are 4,4-isopropylidene orthocr'esol,4,4'-isopropylidenebis(2-phenylphenol) and 4,4'-isopropylidenebis(2,6dichlorophenol). Other diphenols such as '4,'4'-sulfoxyldiphenol and4,4'-oxydiphenol can be used in making the polymers of this invention.Theorganic clihydroxy compound used to make the chainterminatedpolycarbonate resins of this invention can be a pure compound or amixture of such compounds. T "is a monovalent radical formed by thereaction of a chain terminator of this invention with an end group. WhenAr and Ar are both 1,4-phenylene, the polymer has recurring unitscorresponding to the structure:

and when in addition'B is isopropylidene, the polymer of this inventionhas a structure corresponding to the forin which T is a radical obtainedfrom the chain termina- 'tor. Subscript n is a positive integer greaterthan 20 and preferably greater than 40.

The polymers of this invention can be made by modifying known techniquesfor making polycarbonate resins such as by the phosgenation of organicdihydroxy compound or by the reaction of an organic dihydroxy compoundwith a bischloroformate, such modification comprising the addition of achain terminator of this invention to the reaction mixture.

The following examples are illustrative of the invention but theinvention is not limited thereto.

Example I To a solution of 250 grams of sodium hydroxide dissolved in 3liters of water there are added with stirring, 570 grams of4,4'-isopropylidenediphenol and 2.5 liters of methylene chloride. Theresulting mixture is poured into a 10 liter three-mouthed flask. Theflask and contents are placed in a constant temperature bath maintainedat a temperature of between 26 C. and 27 C. The contents are stirredvigorously and phosgene gas is led into the flask below the surface ofthe liquid through a sintered glass tube until an end point at a pH of 7is reached. To part of the emulsion thus formed is added 2.5 molepercent, based on ,1 part of the 4,4- isopropylidenediphenol previouslyadded, of dipropylene glycol mono-n-butyl-ether. There is then added asolution containing 75 milliliters of Water, 9 grams of sodium hydroxideand 2 grams of 4,4-isopropylidenediphenol. Stirring is continued for 1hour and 1 milliliter of a 65 percent aqueous solution ofbenzyltrimethylammonium chloride is then added as a catalyst. Theresultant emulsion is again stirred until it separates into two layers.The supernatant water is decanted and most of the methylene chloride isthen volatilized by heating the solution. The viscous mass thus obtainedis put on a glass plate, air dried overnight and then further dried in avacuum oven at a temperature of between 110 C. and 120 C. The product isa dense solid polymer. A melt of this polymer at 290 C. is transparentand has a very light tint at 340 C. (Unsatisfactory polycarbonate resinsdecompose or darken considerably at these temperatures.) This chainterminated polycarbonate resin has a melt viscosity at 310 C. of 664poises obtained using the equipment and technique described by Karam etal. in A New Melt Viscometer, Modern Plastics, volume 32, number 7,March 1955, at a shearing stress of 700,000 dynes per square centimeter.This polymer has a K value of 57. K is equal to 1,000 k and k iscalculated from the Fikentscher equation.

wherein N is the viscosity of a solution of the sample relative to theviscosity of the solvent and c is the concentration of the sample in thesolution. The solvent used in this test is dioxane. The polymer obtainedin this example has excellent thermal stability. Its viscosity decreaseafter being held at 310 C. for 30 minutes is very slight.

log N,==

Example 11 The procedure of Example I is repeated using the samematerials and proportions except that 2.5 mol percent, based on the4,4'-isopropylidenediphenol as in Example I of ethylene glycolmonophenyl ether is substituted for the glycol ether of Example I as thechain terminator. This chain terminated polycarbonate resin has a stablemelt at 340 C. This polymer has high thermal stability. The viscosity ofthis polymer after being held at 310 C. for 30 minutes is only slightlyless than the initial viscosity.

Example II] To a solution of 230 grams of sodium hydroxide in 3 litersof water contained in a reactor are added with stirring 570 grams of4,4-isopropylidenediphenol and 2.5 liters of methylene chloride. Theresulting liquid mixture is maintained at a temperature of between 26 C.and 27 C. The mixture is stirred vigorously and phosgene gas is fed intothe reactor through a sintered glass tube situated below the liquidsurface until the pH of the liquid drops to 7. To 0.1 part of theemulsion thus formed are added 1 mole percent, based on 0.1 the amountof 4,4-isopropylidenediphenol previously added, of ethylene glycolmonomethyl ether 9 grams of sodium hydroxide, and 75 milliliters ofwater. Stirring is continued mechanically overnight. The materialseparates into two layers. The supernatant water is decanted andmethylene chloride is then volatilized by heating. The viscous mass thusobtained is put on a glass plate, air dried overnight and then furtherdried in a vacuum oven at a temperature of between C. and C. The productis a dense polymer having a molecular weight over 10,000, excellentthermal stability, and low melt viscosity. It can be fabricated intostrong, tough films, filaments, and other shaped articles.

Examples IV through V] The procedure of Example III is repeated usingthe same materials and proportions except that 2.5 mole percent based onthe 4,4'-isopropylidenediphenol as in EX- ample III of one of each ofthe following materials is substituted for the glycol ether of ExampleHI: Example IV, tributylene glycol monocyclohexyl ether; Example V,propylene glycol monododecyl ether; Example VI, ethylene glycolmonononyl ether. The products are high molecular weight polycarbonateresins of outstanding thermal stability and low melt viscosity. Shapedarticles can be made easily from their melts by injection molding,extrusion, casting, and other standard techniques.

Similar excellent results are obtained using other chain terminators ofthis invention as above defined including those terminators specificallydenominated.

The chain terminated polycarbonate resins of the present invention arecharacterized by high molecular weight, exceptional thermal stabilityand low melt viscosity. These resins are usually transparent and rangefrom colorless to slightly tinted. They can be mixed with dyes,delusterants, pigments, plasticizers, reinforcing materials and withother polymers. They are easily fabricated into useful articles such asfilms, fibers, sheets, tubes, rods and the like from a melt or solutionthereof by conventional shaping techniques such as molding, casting, andextruding. The resins can also be used to make laminates, such as safetyglass and as protective or decorative coatings.

That which is claimed is:

1. A high molecular weight, thermally stable polycarbonate resinterminated with a glycol ether of the formula in which R is ahydrocarbon radical having from 1 to 12 carbon atoms and is free ofaliphatic unsaturation, R" and R' are independently selected from thegroup consisting of H, methyl and ethyl, and the sum of carbon atoms inR" and R' is from 0 to 2, and n is a positive integer from 1 to 3.

2. A high molecular weight, thermally stable chain terminatedpolycarbonate resin according to claim 1 in which the glycol ether isethylene glycol monomethyl ether.

3. A high molecular weight, thermally stable chain terminatedpolycarbonate resin, according to claim 1 in which the glycol ether isdipropylene glycol mono-n-butyl ether.

4. A chain terminated polycarbonate resin having recurring units of thestructure in which the hexagons represent benzene rings and B isselected from the group consisting of a divalent hydrocarbon radical,oxygen, and sulfonyl, the chain terminator having a structure of theformula in which R is a hydrocarbon radical having from 1 to 12 carbonatoms and is free of aliphatic unsaturation; R" and R" are independentlyselected from the group consisting of H, methyl and ethyl, and the sumof the carbon atoms in R and R' is from 0 to 2, and n is a positiveinteger from 1 to 3.

5. A chain terminated polycarbonate resin according CH3 0 (3H1 n inwhich n is an integer greater than 40 and T is a radical obtainable byremoving the hydroxyl hydrogen from dipropylene glycol mono-n-butylether.

References Cited in the file of this patent UNITED STATES PATENTS1,921,756 Kienle Aug. 8, 1933 20 2,889,312 Szayna June 2, 1959 2,950,266Goldblum Aug. 23, 1960 ERNEST w. SWIDER UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No, 3, O8O 342 March 5 196,3

Lieng-Huang Lee et a1.,

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 2 lines 62 to 65 and column 5 lines 3 to 6 the formulae shouldappear as shown below instead of as in the patent:

Signed and sealed this 8th day of October 1963,

(SEAL) Attest:

snw n L Attesting Officer Acting Commissioner of Patents I 7

1. A HIGH MOLECULAR WEIGHT, THERMALLY STABLE POLYCARBONATE RESINTERMINATED WITH A GLYCOL ETHER OF THE FORMULA